Interference by radiotherapy in patients with cardiac implantable electronic devices

Radiotherapy (RT) is a cornerstone in cancer therapy. The annul number of patients with cardiac implantable electronic devices (CIEDs; PM, ICDs and CRT) undergoing radiotherapy is increasing annually. Management of these patients is challenging as CIED interference and dysfunction caused by RT is rare, but can lead to serious adverse clinical events. Recommendations on how to manage CIED-carriers during RT exist but prospective data are scarce.

In this study we report our experience of CIED interference during radiation therapy in a multidisciplinary tertiary care teaching hospital.

We conducted an observational, real-world, prospective, single-center study enrolling all patients with CIEDs undergoing RT from January 2023 to October 2024. All devices were MRI-conditional. Management during RT and frequency of device check-up were performed according to an EHRA algorithm based on risk stratification according to device type, pacemaker-dependency and type and dose of radiation on the generator. In general, patients were monitored during radiation, but CIEDs were not reprogramed and no magnets were placed on the devices during RT. The goal of this study was to analyze safety of the algorithm and to eventually detect CIED dysfunctions.

A total of 3.278 patients underwent RT at our center, 52 of them were CIED-carriers (1.6%). The most represented malignancy was prostate cancer (34.6%), followed by lung (17.3%) and esophageal cancer (7.7%). Conventional transvenous pacemakers were the most represented type of CIED (41 patients; 78.9%), followed by transvenous ICDs (7 patients; 13.5%), CRT-P (2 patients; 3.9%), CRT-D and leadless pacemaker (1 patient each; 1.9%). Medtronic was the most represented manufacturer (24 devices; 46.2%), followed by Biotronik (21 devices; 40.4%), Boston (3 devices; 5.8%), Sorin and St. Jude/Abbott (2 devices; 3.9% each). 8 patients (15.4%) were equipped with remote monitoring during the entire duration of RT.

In 51/52 patients (98.1%) we did not observe any signs of CIED dysfunction on telemetry, regular ECGs and device check-ups. However, anti-tachycardia therapy was deactivated during the last CIED follow-up at the end of RT in one patient with an implanted VVI-ICD (1/52; Biotronik). No adverse clinical event was observed as a result of the malfunction and the device could easily be reprogrammed.

Management following the EHRA algorithm with regular CIED follow-ups during RT proofed to be safe. In the vast majority of patients with CIEDs undergoing RT no dysfunction of the device was observed. However, inactivation of antitachycardia therapy was observed in a single chamber-ICD indicating that regular follow-ups or prophylactic telemonitoring is necessary during RT.